Performance Evaluation On The Rapid Detection Of Hepatitis B Surface Antigen By Gold-immunochromatography Assay (GICA)

BackgroundHepatitis B surface antigen (HBsAg) is the first serum marker appearing during the course of hepatitis B virus (HBV) infection, which could be detectable before the onset of clinical symptom. The prevalence of HBV infection is high in China. The ability of detecting HBV infection should be improved in order to safeguard populational health, promote economical and social developments. There are some factors such as window period, assay quality and other uncertain factors existing in experiments which influence the detection of HBV infection. With the development of clinical laboratory technology, the methods of detecting HBsAg have changed. Point of care testing (POCT), one of the new clinical hotspots, plays an important role in diagnosing and treating timely, improving efficacy and shortening turn around time (TAT). Gold-immunochromatography (GICA) for detecting HBsAg is one kind of POCT. According to the situation of HBV infection in China, it is significantly important to choose an assay which has quick reaction, high sensitivity, low cost and good quality.ObjectivesIt aims to know the change of HBsAg detection methods and to evaluate the performance of the new detection system, which can advance the laboratory quality and promote the application of new, rapid and simple detection system in clinical laboratories.ContentsFirstly, analyze descriptively the HBV marker detection methods in Shanghai medical institutions from2006to2010. Secondly, evaluate the performance of GICA for the rapid detection of HBsAg.MethodsShanghai medical institutions took part in the external quality assessment (EQA) of HBV marker detection which was organized by Shanghai Center for Clinical Laboratory (SCCL) twice annually. The results of the second assessment in October annually from2006to2010were collected and analyzed descriptively. Through detecting the clinical specimens and definite-valued quality control materials from National Center for Clinical Laboratory, the sensitivity and interference testing results of GICA for the rapid detection of HBsAg were evaluated. A total of510specimens were collected and detected for HBsAg by both enzyme-linked immunosorbent assay (ELISA) and GICA, and the concordance between the two assays was evaluated. The specimens with different results by the two assays were performed for the confirmatory test. The specificity, positive predictive value, negative predictive value and accordant rate of GICA were calculated.ResultsThrough analyzing the EQA results of HBV serum markers, we found that ELISA (enzyme immunoassay) was the major method for detecting HBV serum marker in Shanghai medical institutions from2006to2010.The proportion decreased from83.12%in2006to66.88%in2010. The trend of the application of luminescence quantity (or half-quantity) method increased. The proportion of GICA increased gradually from1.91%in2006to5.19%in2010. The Shanghai medical institutions which detected HBV serum markers by GICA were major in community health service and private hospitals. Through analyzing the EQA results in2009, the study found that the results of only71.43%laboratories detecting HBsAg by GICA scored full marks, and the disqualification rate was high. In this EQA, the six laboratories with the disqualification results were all performed with GICA.Through evaluating the performance of GICA for the rapid detection of HBsAg, the analytic sensitivity was4.0IU/mL(or2.0ng/mL). Since1995, it was required that the reagents for HBsAg testing should be detected for every batch, and the sensitivity of ELISA should be<0.5ng/mL. But it was not required for GICA. Lipidemia (18.5mmol/L) had no interference to the results of the detection. Hemoglobin and bilirubin had interference on the HBsAg detectionThrough the comparison of GICA and ELISA by detecting510specimens, the study found that the serious problem of GICA was due to high false negative rate. There were18false negative samples in low positive samples (ELISA OD<1.0) The sensitivity and specificity of GICA were92.53%and100%respectively.According to the results of the study, it suggests that GICA is only suitable for the preliminary screening of HBsAg among blood donors and emergency operation patients or in township hospitals. The results of GICA can not be as the reference for the clinical diagnosis and treatment.